BIOL240 Lecture Notes - Lecture 10: Auxotrophy, Growth Medium, Wild Type

• School: University of Waterloo
• Department: Biology
• Course: BIOL240
• Professor: Josh Neufeld

Document Summary

Organization of bacterial genomes: single chromosome/plasmid, (cid:862)repli(cid:272)o(cid:374)(cid:863, plasmid number is regulated, bacteriophage dna can be present too, (cid:862)housekeepi(cid:374)g ge(cid:374)es(cid:863) (cid:374)ot fou(cid:374)d i(cid:374) plas(cid:373)id. Mutations: bacteria are ideal for research, one chromosome, easy to find mutation. Studying mutants: compares wild-types with mutants, purpose: to identify alleles and genotype, genotype = all alleles. Isolating cells with a wanted genotype: using growth properties, selectable mutations -> growth advantage, phenotypic selection, growth medium -> inhibit microbes lacking desired gene, antibiotic selection, cells do the work, screening. Types of mutations: silent, mutation occurs -> amino acid still the same, third position of codon, missense, change in codon -> amino acid is different, nonsense, forms an early stop codon, frameshift. Insert/delete: mrna reads it different -> different amino acid. Reversion: a mutation that (cid:272)orre(cid:272)ts a (cid:373)eta(cid:271)oli(cid:272) a(cid:271)(cid:374)or(cid:373)ality (cid:271)a(cid:272)k to (cid:862)origi(cid:374)al for(cid:373)(cid:863: problem: hard to determine mutation rates or transduction rates, double/triple auxotroph mutant strains -> decreases spontaneous reversion mutation.